The research projects on the organism Saccharomyces cerevisiae will include the following: 1) Continued characterization of conditional, mitochondrially inherited mutants and their revertants. This characterization will be at the physiological as well as at the molecular gene-product relationship, in particular the mutant related lesions that occur in the subunits of cytochrome oxidase and of ATPase. 2) Further mapping of the yeast mitochondrial genome. These studies will include the use of conditional mutants, antibiotic resistant mutants and Mn ions induced deletions to saturate the yeast mitochondrial genome, particularly in the omega region. 3) The glycolytic mutants that have already been isolated, in particular those with lesions in the metabolism at the 6-carbon level, will be characterized. So will the revertants that are currently being isolated. In collaboration with Dr. R. Shulman at Bell Laboratories, the mutants and revertants will be examined for the interconversions of phosphorylated intermediates using 31P-NMR spectroscopy. 4) Studies on the regulation of maltase induction in yeast at the genetic, transcriptional and translational level will be continued. In addition, the maltase structural gene will be cloned by transforming E. coli, making use of the plasmid PMB9. The role of several yeast regulatory genes will be studied. 5) Finally, some time will be spent on the biology of the yeast 2 micron plasmid; its genetics and possible function.